Information technology has provided new ways of publishing books, newspapers, magazines and periodicals. Electronic books (“e-books”) can be purchased and downloaded from e-bookstores online and read on various devices, such as personal computers, personal digital assistants (PDAs), pocket-PCs, mobile phones, media player/recorders, dedicated e-book readers, etc. An e-book is typically a collection of digital objects or documents, which are packaged and formatted with the intention of being displayed on a device or read by a speech generating application. E-books can be distributed over a network as a sequence of images, for example, one image for each page. E-books that are distributed over a network (e.g., the Internet, wireless network) using Hypertext Mark-up Language (HTML) can be read using a standard browser (e.g., Microsoft® Internet Explorer).
Conventional e-book technology suffers several drawbacks. For example, exploring an e-book typically requires horizontal motion (flipping through pages) and vertical motion (scrolling within every page), which makes regular sequential reading of book pages frustrating. Another drawback is the poor use of free space on large display screens and limited space on small display screens.
In addition to the deficiencies described above, conventional e-book distributors and other online content resources do not provide a comprehensive online source of aggregated reference materials related to content.